Charles e



- (No Model.)

- U. E. SCRIBNER.

POLARIZED SIGNAL BELL.

,613. Patented Nov. 16, 1897.

q H WP 3 TTTI.

J12 yezzzor: I (Ear/295 .Scri 1262 UNTTED STATES PATENT @rmcn.

CHARLES E. SCRIBNER, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE VVESTERN ELECTRIC COMPANY, OF SAME PLACE.

POLARIZED SIGNAL-BELL.

SPECIFICATION forming part of Letters Patent No. 593,613, dated November 16, 1897. A n n fil d November 25, 1895. Serial No. 570,059. (No model.)

No. 410,) of which the following is a full, clear,

concise,and exact description,reference being had to the accompanying drawing, forming a part of this specification.

My invention concerns polarized signalbells for telephone-lines, in which the bells are subjected to continuous currents in the line tending to interfere with the ringing of the bell by alternating currents.

The invention aims to provide such an arrangement of circuits in the bell that continuous or unvarying currents circulating in its coils may leave its cores neutral, but that alternating currents may excite the magnet to operate the bell.

The invention consists in the use in apolarized signal-bell of ordinary type of two reverse windings upon the electromagnet con- 2 5 nected in parallel, the circuit through one of the windings being characterized by high selfinduction. The magnetic effects of the two windings upon the core are made equal, so that while a continuous current flows in the 0 coil the cores remain neutral. When,however,

an alternating current is produced in the circuit containing the bell, the passage of the current through the branch having the greater impedance is obstructed, nearly the entire 3 5 current being diverted through the other branch. The magnetic effect of the winding in thelatter branch is thus not balanced by a counter magnetizing effect of the other winding and acts to throw the armature into oscillation.

In some telephone-exchange systems each substation is furnished with a local storage battery which is continuously charged during the idleness of the line by a current in 5 the line-circuit. It has been found in practice that the efficiency of operation of ordinary bells when placed in such a circuit is seriously impaired by this continuously-flowing current. The improved bell of this invention is particularly adapted for such use,

.through coil a.

since the bell remains unaffected by the contlnuously-flowing charging-current, but is highly sensitive to alternating signaling-currents.

. scription.

The polarized signal-bell at the substation may comprise the usual electromagnet a, a centrally-pivoted armature a for the magnet, and a permanent magnet a for imparting polarity to the armature. The pivoted armature a is provided with a tongue carrying a hammer oscillating between gongs a The electromagnet a has wound upon it two coils a and a the two serially-connected helices on the two limbs of the magnet being considered as one coil. The coils of and a are wound or connected reversely, so that each tends to neutralize the magnetizing effect of the other. These coils o and a are located in different parallel branches 1 and 2, respectively, of the circuit containing the bell. The branch 2 includes, in addition to the magnetcoil, an inductive resistance-coil Z7 to impede variations of the current through the coil (1 The necessary high impedance or self-induction in this branch may of course be attained otherwise than by the use of a separate coil in the circuit, but this device is found to be a satisfactory expedient. The coil a may have a greater number of turns than the coil a or may have less resistance, in order that a continuous current flowing in the circuit may be divided equally between the coils or may have equal magnetizing effects in the two coils. Under that condition obviously the core of the magnet will remain neutral, and the armature a will lie indifferently upon either side. When, however, an alternating current is produced in the circuit, its passage through winding of is obstructed by the self-induction of the circuit, and the greater portion of the current is diverted The effect of this coil on the core is then not neutralized to any consider able extent by the current in winding a and produces an alternating magnetization of the cores, which throws the armature a into vibration and thus operates the bell.

This bell is shown in the circuit 3 t of a telephone-line in series with a local storage battery 0 of two cells. At the substation the usual telephone-switch d is provided, which,

gether with the secondary winding of the same induction-coil. At the central station this circuit is completed through a chargingbattery or other source of current g, an impedance-coil h and an annunciator i being included in the two line conductors 3 and 4, respectively. The charging-battery g is supposed to be common to a number of telephonelines, and the coils 7L and 1' act as inductive resistances to prevent the shunting of telephon ic current from one line to another. The usual spring-jack 7D- in the telephoneswitchboard has its two contact-pieces connected with the two line conductors. A plug Z is shown which may constitute one member of a pair for uniting lines, the plug-circuit 7 8 being led to the switch-springs of a callingkey m, by means of which a generator 12 of signaling-current may be looped into circuit with the plug. During the idleness of the line a current flows continuously from battery g through the line, through the two branches 1 and 2, including the bell-windings, and through the local storage battery 0 at the substation, charging this battery at a sufficient rate to compensate for the use of current from the battery. As before stated, the bell remains inert as to this unvarying current. .Vhen connection is made with the line by means of plug Z and a signaling-current from generator or is transmitted over the line, this alternating current is unequally divided between the two windings of the bell and rings the bell in the manner traced.

I claim as new and desire to secure by Letters Patent- The combination with a telephone-line including a local storage battery in the line at a substation and a charging-battery therefor, and provided with means for producing al ternating currents in the line, of an electric bell whose electromagnet is provided with two differential windings in dillferent parallel branches of the linecircuit, one of which branches is constructed to have high impedance, whereby the bell remains neutral. to the charging-current but may be operated by alternating current, substantially as de scribed.

In witness whereofI hereunto subscribe my name this 17th day of October, A. 1). 1895.

CHARLES E. SCRIBNEH.

\Vitnesses:

ELLA EDLIER, llIYRTA 1 GREEN. 

